Texas has begun a program that could lead to private companies doing routine maintenance on interstate highways to save money. Acording to sources, the Texas Department of Transportation is considering outsourcing routine upkeep on stretches of interstates. The work would include repaving, mowing, litter pickup and sign repair.  A five-year pilot project started this summer. The $26 million program involves an Australian company, Transfield Services, and a 100-mile stretch of I-45 in the Houston area.  TxDOT spokeswoman Kelli Reyna says the anticipated savings would involve less overtime work for state maintenance employees. The agency has projected up to $120 million in savings over five years.